Wrap-spring, variable speed drive arrangement

Abstract

Oscillatory motion of a first end of a lever arm is converted to incremental rotational motion of an output shaft connected to a second end of the lever arm. The second end oscillates with an amplitude determined by a fulcrum adjustable along the lever arm. The output shaft is coupled to the second end of the lever arm by a wrapped spring arrangement.

What is claimed is: 
     
       1. A speed control arrangement for varying the rotation imparted to an output shaft having means for driving movie film a first shaft of a power source, said arrangement comprising a lever arm having first and second ends, said first end being connected eccentrically to said first shaft in a manner to exhibit oscillations therein when said first shaft rotates, said output shaft being coupled to said second end by first and second springs wrapped about said output shaft, and a fulcrum adjustable along said lever arm for controlling the amplitude of oscillations in said second end, said first and second springs being connected to said second end in a manner to convert oscillations in said second end to rotation of said output shaft; said means for driving comprising a sprocket wheel affixed to said output shaft for driving said film. 
     
     
       2. A speed control arrangement in accordance with claim 1 also including means for rotating said first shaft.